Power consumption and form factors in portable systems, such as mobile phones, third-generation (3-G) wireless systems, and personal digital assistants (PDA), are a significant concern, particularly due to the desire to increase battery life and reduce size. Memory devices within portable systems are a significant part of the total power consumption. Typically, SRAM arrays are more power efficient than DRAM arrays and, thus, are conventionally used in portable systems. DRAM arrays, however, are typically more dense than SRAM arrays and thus DRAM arrays have a smaller form factor. The memory size used in portable systems is growing, i.e., currently the typical memory size is 4 Mbit but will soon be 8 Mbit. Thus, the increased density of DRAM arrays will be desirable for use in mobile communication systems.
One type of memory device that has been discussed as a possible replacement of SRAMs for portable systems is known as "pseudo SRAM." Pseudo SRAM uses a non-multiplexed SRAM type interface with a DRAM core. Advantageously, the SRAM type interface requires less power than a conventional multiplexed address DRAM interface. Thus, pseudo SRAM provides a small form factor because of the DRAM core and yet provides some power savings because of the SRAM interface. Unfortunately, a major drawback to pseudo SRAM is that the DRAM core consumes more power than an SRAM core. Thus, it is desirable to reduce the power consumption of a DRAM core in pseudo SRAM.